1. Field of the Invention
This invention is in the field of safing and arming devices for spin stabilized projectiles containing high explosive bursting charges.
2. Description of the Prior Art
Explosive projectiles commonly include safing and arming devices which prevent premature firing of the main charge. Generally, a safing and arming device comprises a barrier which blocks the firing train between the detonator and the bursting charge until after the projectile has been launched. Arming of the projectile is accomplished by means of a release mechanism which causes the barrier to move out of the firing train, thereby allowing detonation to occur. In most prior art devices, the release mechanism has comprised mechanical means responsive to either centrifugal force or the force of setback, or both. These mechanical means have generally required a large number of moving parts, making them impractical for use in very small caliber, such as 20-30 mm, projectiles which have limited volumetric capacity. In addition, in many cases, the response time of the release mechanisms is too short, permitting detonation of the projectile too soon after launching. Premature detonation is clearly undesirable since it can cause damage to the platform or airplane from which the projectile is fired, or endanger the launch crew or other friendly troops.
One safing and arming device which was developed in an attempt to overcome some of the aforementioned problems is disclosed in U.S. Pat. No. 4,770,096 ('096) to Maruska et al. In the '096 device, the centrifugal barrier for blocking the firing train is initially held in place by two restraints: a setback tab, which is rendered inoperative by large forces of linear acceleration when the projectile is launched, and a barrier latch, which is bent out of contact with the barrier by a pyrotechnic actuator activated by an arming signal from the projectile's electronic fuzing system after certain predetermined conditions, such as the passage of a predetermined amount of time, have been met.
In the '096 device, the circuitry for producing the arming signal which activates the pyrotechnic actuator for the barrier latch adds to the cost and complexity of the device's electronic fuzing system. Furthermore, the electronic components of the fuzing system and the explosive charge in the pyrotechnic actuator may malfunction in certain thermal and electromagnetic environments. Therefore, there is a need for an improved mechanical alternative to the electronic and pyrotechnic barrier release means used in the '096 device.